This invention relates to the art of image forming by ink-jet recording. More particularly, the invention relates to an image forming apparatus capable of forming an image that represents a satisfactory three-dimensional effect by producing undulations in accordance with the design of the original picture.
Providing images with a three-dimensional effect by producing undulations in accordance with the design of the original picture is one of the current practices in the printing industry. A way to implement this printing approach is by overlaying image prints on one image-receiving sheet through ink-jet recording.
For example, JP 2000-318140 A discloses a method in which a page image divided into a plurality of planes is acquired from a host computer and the individual plane images are formed in superposition as solid ink layers on the same image-receiving sheet (medium) by means of an ink-jet printer, whereby undulations are formed to produce an image having a three-dimensional effect.
JP 2001-225459 A discloses a method of forming an image with an ink-jet printer, characterized in that normal printing with normal ink employing a normal ink printing head and expanded ink printing with transparent expandable ink employing an expandable ink printing head are performed in superposition, thereby creating an image with a three-dimensional effect.
However, according to the method disclosed in JP 2000-318140 A, one and the same ink-jet head is employed throughout the printing cycle, so the images formed in the respective planes are of the same height and undulations that are reasonably faithful to the three-dimensional effect of the real world cannot be formed with high degree of freedom. In addition, image formation is quite time-consuming since undulations are formed by repeating the image recording process with the same ink-jet head.
On the other hand, according to the method disclosed in JP 2001-225459 A, the image per se is recorded by a normal ink-jet system and undulations are formed by the expandable ink; therefore, a greater three-dimensional effect can be expressed and still only a short time is required to form the image.
However, the method disclosed in JP 2000-318140 A and other conventional ink-jet based methods of forming an image having undulations are not capable of representing other features than the three-dimensional effect, such as the texture of constituent elements of the original picture.